【摘要】 采用二因素三水平法设计模拟氮(N)、硫(S)沉降的盆栽试验,以Na2SO4为硫源、46%CO(NH2)2为氮源,其中氮沉降梯度为N1(0 kg hm-2 a-1)、N2(50 kg hm-2 a-1)、N3(100 kg hm-2 a-1),硫沉降梯度为S1(0 kg hm-2 a-1)、S2(15kg hm-2 a-1)、S3(30 kg hm-2 a-1).模拟试验6个月后,测定尾巨桉(Eucalyptus urophylla×Eucalyptus grandis)和杉木(Cunninghamia lanceolata)幼苗的SPAD值、可溶性蛋白含量、净光合速率(Pn)和叶绿素荧光参数,分析探讨氮、硫沉降处理下两树种幼苗光合特性的响应机制.结果表明:与空白对照组相比,单一中氮沉降显著促进两树种幼苗Pn的上升(P<0.05),且单一高氮沉降显著促进杉木幼苗可溶性蛋白含量的上升(P<0.05),表明单一氮处理在一定程度上提高了两树种幼苗的光合能力.尾巨桉幼苗各光合指标受单一硫沉降胁迫的影响较杉木幼苗更为显著,前者的SPAD值和可溶性蛋白含量在中硫处理下均显著下降(P<0.05),Pn反之;而后者仅SPAD值在中、高硫处理下显著上升(P<0.05).氮、硫复合沉降下,尾巨桉幼苗各项指标未见明显变化(P>0.05);杉木幼苗仅中氮高硫组的SPAD值和高氮高硫组的可溶性蛋白含量显著上升(P<0.05).综上,与单一氮、硫沉降相比,氮、硫复合沉降的交互效应并未显著增强两树种幼苗的光合特性,但两树种幼苗间对模拟氮、硫沉降的响应和耐受机制存在差异.更多还原

【Abstract】 To evaluate the response mechanisms of Eucalyptus urophylla × Eucalyptus grandis and Cunninghamia lanceolata seedlings to simulated nitrogen(N) and sulfur(S) depositions, the two factors and three levels method was used for a pot experiment with Na2SO4 as sulfur source and 46% CO(NH2)2 as nitrogen source. Three levels of Na2SO4 and 46% CO(NH2)2included: low-S(0 kg hm-2 a-1), medium-S(15 kg hm-2 a-1), high-S(30 kg hm-2 a-1), and low-N(0 kg hm-2 a-1), medium-N(50 kg hm-2 a-1), high-N(100 kg hm-2 a-1), respectively. The SPAD value, soluble protein content, net photosynthetic rate(Pn) and chlorophyll fluorescence parameters in leaves of the seedlings among different treatments were measure d after six months. The results showed that, compared with the control group(N: 0 kg hm-2 a-1, S: 0 kg hm-2 a-1), single medium-N deposition significantly increased Pn of seedlings of both species(P < 0.05), and single high-N deposition significantly increased the soluble protein content of C. lanceolata seedlings(P < 0.05), showing that single N deposition partly improved the photosynthetic capacity of seedlings of both species. The effec ts of single S deposition on photosynthetic indicators of E. urophylla × E. grandis seedlings were more obvious than on those of C. lanceolata seedlings: For E. urophylla × E. grandis seedlings, SPAD value and soluble protein content decreased but Pn increased significantly under single medium-S deposition(P < 0.05); but for C. lanceolata seedlings, only SPAD value increased significantly under single medium-S deposition and single high-S deposition(P < 0.05). Under N and S complex depositions, none of the photosynthetic characteristic factors of E. urophylla × E. grandis seedlings showed significant change(P > 0.05), and only SPAD value and soluble protein contentof C. lanceolata seedlings increased signifi cantly in the medium N-high S treatment and high N-high S treatment(P < 0.05), respectively. In conclusion, compared with single N and S deposition, the interactive effect of N and S complex depositions does not signifi cantly promote photosynthetic characteristics of E. urophylla × E. grandis or C. lanceolata seedlings; seedlings of the two species have different responses to simulated N and S depositions.更多还原